I'm a mechanical and aerospace engineer and I can assure you the magnet trick is NOT going to affect any other air conditioner units. For Pete's sake....who comes up with such ridiculous theories????
There is a magnet proximity switch on the balcony door jamb which, when the door is open, the switch is "broken" and the A/C unit turns off to keep it from running while the door is open. Your security system in your house operates the same way. There is a magnet (or metallic sink) on the door so when the door is closed, the switch senses the magnet in the door and the switched is "closed" or "on" and allows the A/C to operate.
To run the A/C with the door open you only need to place a magnet (tape it) on or near the proximity switch in the jamb. This keeps the switch "closed" or "on."